Non-Newtonian Blood Flow in the Right Coronary Artery

2004 ◽  
Author(s):  
Narcisse A. N’Dri ◽  
Don P. Giddens
Keyword(s):  
Blood Flow ◽  
Power Law ◽  
Human Subjects ◽  
Flow Behavior ◽  
Circulatory System ◽  
Arterial Grafts ◽  
Commercial Code ◽  
Significant Difference ◽  
Time Average ◽  
The Right

Understanding blood flow in the circulatory system and how it affects intimal thickening is important with respect to atherogenesis and also for the design of vascular treatment devices such as stents and arterial grafts. While the assumption of Newtonian blood flow in large arteries is widely accepted by many investigators, questions remain unanswered for blood flow in the coronaries. In this study we investigate Non-Newtonian blood flow behavior in both the right and the left coronaries. We use a commercial code (FIDAP) to compare the Newtonian model to four Non-Newtonian models (Power law, Casson, Carreau and Quemada models) widely used in the literature. The coronary geometries were reconstructed from MRI images of human subjects. We found a significant difference in time average WSS between the power law and the Newtonian models. Also a difference in time average WSS is observed for the Quemada model. On the other hand, No significant difference is observed for the Newtonian, Casson and Carreau models.

Lack of effect of peripheral nervous blockade on nocturnal fluctuations in lower-leg subcutaneous blood flow in man

1993 ◽  
Vol 84 (3) ◽  
pp. 297-304 ◽  
Author(s):  
J. H. Sindrup ◽  
L. J. Petersen ◽  
J. Kastrup ◽  
H. Wroblewski ◽  
J. K. Kristensen
Keyword(s):  
Blood Flow ◽  
Data Storage ◽  
Human Subjects ◽  
Lower Leg ◽  
Tissue Blood Flow ◽  
Storage Unit ◽  
Significant Difference ◽  
Blood Flow Increase ◽  
Subcutaneous Blood Flow ◽  
The Right

1. The local subcutaneous adipose tissue blood flow was measured simultaneously in the right and left lower legs of 10 normal human subjects under outpatient nocturnal conditions. The 133Xe-wash-out technique, portable CdTe(Cl) detectors and a portable data-storage unit were used for the measurement of blood flow. 2. The purpose of the study was to unveil the possible role of centrally controlled nerve fibres to the measurement area as mediators of a previously described nocturnal subcutaneous hyperaemia of 2 h duration. Therefore, before the sleeping period, a local nervous blockade was applied immediately proximal to the isotope depot on the right lower leg by the injection of approximately 15 ml of bupivacaine (5 mg/ml) subcutaneously. 3. Control experiments revealed blockade of the baroreceptor vasoconstrictor reflex activity 4 h after application of the local nervous blockade in three subjects examined. 4. Identical nocturnal isotope-wash-out curves were recorded from the two legs. Subcutaneous blood flow was found to increase significantly (P <0.0001) after approximately 1 h of sleep and the hyperaemia persisted for 2 h. 5. A significant positive correlation was detected between the latency periods from going to bed until the onset of the hyperaemia in the right and left lower legs (P <0.001, r = 0.95). 6. No significant difference could be detected between the relative blood flow increase during the hyperaemic phase in the right and left lower legs (P = 0.83). 7. It is concluded that the present data seem to rule out a central nervous factor(s) as the eliciting mechanism of the nocturnal subcutaneous hyperaemia. A circulating humoral factor(s) might be involved, although modification by local metabolic factors cannot be excluded. The possible physiological significance of the nocturnal hyperaemia is discussed.

Evidence for a dorso-medial parietal system involved in mental transformations of the body

1996 ◽  
Vol 76 (3) ◽  
pp. 2042-2048 ◽  
Author(s):  
E. Bonda ◽  
S. Frey ◽  
M. Petrides
Keyword(s):  
Blood Flow ◽  
Parietal Cortex ◽  
Human Subjects ◽  
Body Position ◽  
The Body ◽  
Right Hand ◽  
Positron Emission ◽  
Superior Parietal Cortex ◽  
The Right ◽  
Mental Transformations

1. The neural systems underlying body-space mental representation were studied by measuring changes in regional cerebral blood flow (CBF) with positron emission tomography in human subjects. 2. The experimental paradigm involved identification of the left or the right hand of the experimenter presented in different orientations or the palm of the subject's right hand. The subjects were required to decide whether it was the left or the right hand that was presented. To perform this task, the subjects had to move mentally the position of their own arm to adopt that of the experimenter's arm. The control condition involved the same type of tactual stimulation without the requirement of mental transformations of the subject's body position. The distribution of CBF was measured by means of the water bolus H2(15)O methodology during the performance of these tasks. 3. Comparison of the distribution of CBF between the experimental and control tasks was carried out to reveal changes specific to the mental transformations of the subject's body. Significant blood flow increases were observed in the caudal superior parietal cortex, including the intraparietal sulcus, and the adjacent medial parietal cortex. These findings demonstrated that there is a dorsomedially directed parietal system underlying mental transformations of the body in interactive relation with external space.

Determinants for outcome of hypoplastic right ventricle with duct-dependent pulmonary blood flow presenting in the neonatal period

1992 ◽  
Vol 2 (4) ◽  
pp. 377-381 ◽  
Author(s):  
Michael L. Rigby ◽  
Micelia Salgado ◽  
Celia Silva
Keyword(s):  
Blood Flow ◽  
Right Ventricle ◽  
Pulmonary Blood Flow ◽  
Pulmonary Valve ◽  
Pulmonary Atresia ◽  
Cross Sectional ◽  
Mitral Valves ◽  
Significant Difference ◽  
The Right ◽  
Pulmonary Valvar Stenosis

SummaryA retrospective study was undertaken of patients with hypoplastic right ventricles, either with pulmonary atresia and intact ventricular septum or critical pulmonary valvar stenosis, and duct-dependent pulmonary blood flow who were investigated at the Royal Brompton Hospital between January 1976 and December 1990. The diagnosis was made on the basis of at least one diagnostic method (cross-sectional echocardiography, cardiac catheterization and angiography, or autopsy). Of the patients, 56 (82%) were found to have an imperforate pulmonary valve or infundibulum (pulmonary atresia), while 12(18%) had critical pulmonary valvar stenosis. The ratio of the diameters of the tricuspid and mitral valvar orifices was measured angiographically during diastole, and the right ventricle was analyzed according to the presence or overgrowth of the inlet, apical trabecular and outlet components. A correlation was made between the severity of the disease and the outcome. The overall mortality was 53% when those not undergoing any surgery were excluded, and significant differences were found between the group dying and those who survived. The incremental risk factors for death were a ratio between the diameter of the tricuspid and mitral valves of less than 0.6; the presence of fistulous communications with the coronary arteries; and obliteration of the apical trabecular component of the right ventricle. There was no significant difference between the group with pulmonary valvar atresia and the group with critical stenosis of the pulmonary valve.

Brain magnetic resonance elastography on healthy volunteers: A safety study

2009 ◽  
Vol 50 (4) ◽  
pp. 423-429 ◽  
Author(s):  
Guang-Rui Liu ◽  
Pei-Yi Gao ◽  
Yan Lin ◽  
Jing Xue ◽  
Xiao-Chun Wang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Magnetic Resonance ◽  
Healthy Volunteers ◽  
Human Subjects ◽  
Magnetic Resonance Elastography ◽  
Tissue Elasticity ◽  
Study Results ◽  
Significant Difference ◽  
The Right

Background: Magnetic resonance elastography (MRE) is a recently developed imaging technique that can directly visualize and quantitatively measure tissue elasticity. Purpose: To evaluate the safety of brain MRE on human subjects. Material and Methods: The study included 20 healthy volunteers. MRE sequence scan (drive signal not applied to external force actuator) and MRE study were separately performed on each volunteer at an interval of more than 24 hours. The heart rate and blood pressure of each volunteer were measured immediately before and after MRE sequence scan and MRE study. Electroencephalography (EEG) was also performed within 2 hours after each scan. The volunteers were asked about their experience of the two scans. Randomized-block analysis of variance (ANOVA) was used to analyze the data of blood pressure and heart rate. Paired t test was used to analyze the data of the two EEG examinations. The volunteers were followed up 1 week after the examination. Results: All procedures were performed on each volunteer, and no one complained of obvious discomfort. No related adverse events were reported during follow-up. There was no statistically significant difference in heart rate or blood pressure. There was a statistically significant difference ( P<0.05) in EEG results in the right temporoparietal region. Increased power was found in the theta, delta, alpha, and beta2 bands. No brain injury was detected by the EEG examinations. Conclusion: Based on the study results, brain MRE examinations are safe to perform on human subjects.

2 Hz Electro-Acupuncture at Yinlingquan (SP9) and Ququan (LR8) Acupoints Induces Changes in Blood Flow in the Liver and Spleen

2012 ◽  
Vol 40 (01) ◽  
pp. 75-84 ◽  
Author(s):  
Wen-Cheng Chou ◽  
Hsu-Jan Liu ◽  
Yi-Wen Lin ◽  
Chin-Yi Cheng ◽  
Tsai-Chung Li ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
The Body ◽  
Arterial Blood ◽  
Flow Perfusion ◽  
Significant Difference ◽  
Specific Organ ◽  
The Mean ◽  
The Right ◽  
Measurement Period

According to the principles of traditional Chinese medicine, channels and collaterals within the body provide pathways through which qi and blood travel, and each channel or collateral is linked with a specific organ. The Yinlingquan (spleen 9, SP9) and Ququan (liver 8, LR8) acupoints represent the sea points of the spleen and liver meridians, respectively, from which qi and blood flow into their specific visceral organs. The purpose of this study was to investigate the changes in blood flow/perfusion in the liver and spleen resulting from the application of 2 Hz electro-acupuncture (EA) to the Yinlingquan (SP9) or Ququan (LR8) acupoints. A total of 18 Spragrue-Dawley rats were randomly divided into three groups of six rats each as follows: sham group receiving sham EA; Yinlingquan (SP9) group receiving 2 Hz EA, applied at bilateral Yinlingquan (SP9) acupoints; and Ququan (LR8) groups receiving 2 Hz EA, applied at bilateral Ququan (LR8) acupoints. The mean blood flow/perfusion of the spleen and liver was recorded using a laser Doppler blood flow monitor prior to EA (representing the baseline), during EA, and post-EA. Each measurement period lasted ten minutes. Nitric oxide levels were also measured from the right femoral arterial blood, following the conclusion of each series of blood flow/perfusion recordings. The results indicate that the sham EA did not increase the mean blood flow/perfusion in the liver or spleen; 2 Hz EA at bilateral Yinlingquan (SP9) acupoints increased the mean blood flow/perfusion in the spleen, but not in the liver. In contrast, 2 Hz EA at bilateral Ququan (LR8) acupoints increased the mean blood flow/perfusion in the liver, but not in the spleen. Nitric oxide levels showed no significant difference between any of the groups at any stage of the measurements. According to the results, we conclude that EA at the Yinlingquan (SP9) and Ququan (LR8) acupoints can increase the blood flow in the spleen and liver, respectively.

Effect of ischaemic exercise training of a normal limb on angiogenesis of a pathological ischaemic limb in rabbits

2009 ◽  
Vol 117 (5) ◽  
pp. 201-208 ◽  
Author(s):  
Mei Shen ◽  
Jing Gao ◽  
Jianan Li ◽  
Juan Su
Keyword(s):  
Blood Flow ◽  
Exercise Training ◽  
Femoral Artery ◽  
High Intensity ◽  
Vegf Mrna ◽  
High Group ◽  
Artery Ligation ◽  
Capillary Supply ◽  
Significant Difference ◽  
The Right

The present study was designed to test the hypothesis that local exercise of a normal limb can promote angiogenesis in a pathological ischaemic limb. New Zealand White rabbits underwent left femoral artery ligation (Lig) and electrode implantation on the right sciatic nerve. The rabbits were randomly assigned to four groups: (i) Lig-N group, which did not receive ES (electrical stimulation); (ii) Lig-High group, which received high-intensity ES (2.5 mA, 40Hz for 1 ms) on the right hindlimb; (iii) Lig-Low group, which received low-intensity ES (0.3 mA, 40Hz for 1 ms) on the right hindlimb; (iv) Double-Lig-High group, which underwent femoral artery ligation on both hindlimbs and received high-intensity ES (2.5 mA, 40Hz for 1 ms) on the right hindlimb. The ES procedure included 5 min of stimulation, followed by 5 min of rest, and was repeated eight times a day for 4 weeks. Collateral circulation was examined grossly by angiography, resting blood flow was measured using the microspheres technique, and capillary supply was evaluated by immunohistochemistry. VEGF (vascular endothelial growth factor) mRNA and protein were analysed by real-time RT (reverse transcription)–PCR and Western blotting respectively. Collateral blood flow in all of the major muscles of the left hindlimb in the Lig-High group was highest among the four groups (P<0.01). Capillary supply (P<0.001), VEGF mRNA (P<0.01) and VEGF protein (P<0.01) in the gastrocnemius muscle increased remarkably in the Lig-High group; no statistically significant difference was observed among the other three groups. In conclusion, angiogenesis associated with an up-regulation of VEGF expression in pathological ischaemic limb may be facilitated by 4 weeks of physiological ischaemic exercise training in a normal limb.

Contributions of Nitric Oxide and Prostaglandins to the Local Increase in Muscle Blood Flow following Manual Acupuncture in Rats

2015 ◽  
Vol 33 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Hisashi Shinbara ◽  
Masamichi Okubo ◽  
Keisaku Kimura ◽  
Kunio Mizunuma ◽  
Eiji Sumiya
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Muscle Blood Flow ◽  
Tibialis Anterior Muscle ◽  
Dependent Manner ◽  
Manual Acupuncture ◽  
Sprague Dawley ◽  
Significant Difference ◽  
Synthase Inhibitor ◽  
The Right

Objective To investigate the contributions of nitric oxide (NO) and prostaglandins (PGs) to the increase in local muscle blood flow (MBF) observed following manual acupuncture (MA). Methods Male Sprague-Dawley rats (n=112; 250–310 g) were injected intraperitoneally with a non-selective NO synthase inhibitor (NG-nitro-L-arginine methyl ester hydrochloride: L-NAME; 10, 50 or 500 mg/kg), a non-selective cyclo-oxygenase inhibitor (indomethacin; 10, 50 or 500 mg/kg), a combination of L-NAME and indomethacin (500 mg/kg each) or saline only under urethane anaesthesia (1.2 g/kg). We used the sparrow pecking technique for 1 min with a stainless steel acupuncture needle (0.20×30 mm) as the acupuncture stimulation method. The stimulus point was on the right tibialis anterior muscle. 51Chromium-labelled microspheres were used for MBF measurement. Results MA increased MBF in the saline-injected group (p<0.001). This increase was partially inhibited by L-NAME in a dose-dependent manner (p>0.05, p<0.05 and p<0.001 for 10, 50 and 500 mg/kg, respectively). On the other hand, indomethacin did not suppress the increase (p>0.05 each for 10, 50 and 500 mg/kg). No significant difference was observed between the inhibitory effects of combined administration of L-NAME and indomethacin and single administration of L-NAME (p>0.05). Conclusions These results suggest that NO is a major factor in the MA-induced increase in MBF, while PGs do not contribute significantly to this increase. As complete inhibition was not achieved by administration of L-NAME±indomethacin, it appears that non-NO and non-PG vasodilators are additionally involved.

Suicidal Ideation and Self-Determination in Institutionalized Elderly

Crisis ◽  
2001 ◽  
Vol 22 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Andrée Fortin ◽  
Sylvie Lapierre ◽  
Jacques Baillargeon ◽  
Réal Labelle ◽  
Micheline Dubé ◽  
...  
Keyword(s):  
Self Determination ◽  
Current Debate ◽  
Elderly Persons ◽  
Rational Suicide ◽  
Institutionalized Elderly ◽  
Significant Difference ◽  
Social Subscale ◽  
Civil Status ◽  
The Right ◽  
Taking Action

The right to self-determination is central to the current debate on rational suicide in old age. The goal of this exploratory study was to assess the presence of self-determination in suicidal institutionalized elderly persons. Eleven elderly persons with serious suicidal ideations were matched according to age, sex, and civil status with 11 nonsuicidal persons. The results indicated that suicidal persons did not differ from nonsuicidal persons in level of self-determination. There was, however, a significant difference between groups on the social subscale. Suicidal elderly persons did not seem to take others into account when making a decision or taking action. The results are discussed from a suicide-prevention perspective.

A Non-Newtonian Fluid Flow Model for the Slip Condition on Blood Flow through a Stenosed Artery using Power-law Fluid

2018 ◽  
Vol 9 (7) ◽  
pp. 871-879
Author(s):  
Rajesh Shrivastava ◽  
R. S. Chandel ◽  
Ajay Kumar ◽  
Keerty Shrivastava and Sanjeet Kumar
Keyword(s):  
Blood Flow ◽  
Fluid Flow ◽  
Newtonian Fluid ◽  
Power Law ◽  
Flow Model ◽  
Slip Condition ◽  
Power Law Fluid ◽  
Stenosed Artery ◽  
Flow Through

DeVega versus ring annuloplasty in severe functional tricuspid insufficiency and their impact on the right ventricle

2019 ◽  
Vol 1 (4) ◽  
pp. 133-139
Author(s):  
Yasser Hamdy ◽  
Mohammed Mahmoud Mostafa ◽  
Ahmed Elminshawy
Keyword(s):  
Right Ventricular ◽  
Tricuspid Valve ◽  
Tricuspid Regurgitation ◽  
Early Postoperative Period ◽  
Tricuspid Valve Repair ◽  
Ring Annuloplasty ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
The Right

Background: Functional tricuspid valve regurgitation secondary to left-sided valve disease is common. DeVega repair is simple, but residual regurgitation with subsequent impairment of the right ventricular function is a concern. This study aims to compare tricuspid valve repair using DeVega vs. ring annuloplasty and their impact on the right ventricle in the early postoperative period and after six months. Methods: This is a prospective cohort study of 51 patients with rheumatic heart disease who underwent tricuspid valve repair for secondary severe tricuspid regurgitation. Patients were divided into two groups: group A; DeVega repair (n=34) and group B; ring annuloplasty repair (n=17). Patients were assessed clinically and by echocardiography before discharge and after six months for the degree of tricuspid regurgitation, right ventricular diameter and tricuspid annular plane systolic excursion (TAPSE). Results: Preoperative echocardiographic assessment showed no difference in left ventricular end-systolic diameter, end-diastolic diameter, ejection fraction and right ventricular diameter, however; group A had significantly better preoperative right ventricular function measured by TAPSE (1.96 ± 0.27 vs1.75 ± 0.31 cm; p=0.02). Group B had significantly longer cardiopulmonary bypass time (127.65 ± 13.56 vs. 111.74 ± 18.74 minutes; p= 0.003) and ischemic time (99.06 ± 11.80 vs. 87.15 ± 16.01 minutes; p= 0.009). Pre-discharge, there was no statistically significant difference in the degree of tricuspid regurgitation, but the right ventricular diameter was significantly lower in group B (2.66 ± 0.41 and 2.40 ± 0.48 cm; p=0.049). After six months of follow up, the degree of tricuspid regurgitation (p= 0.029) and the right ventricular diameter were significantly lower in the ring annuloplasty group (2.56 ± 0.39 and 2.29 ± 0.44 cm; p=0.029). Although there was a statistically significant difference in preoperative TAPSE, this difference disappeared after six months. Conclusion: Both DeVega and ring annuloplasty techniques were effective in the early postoperative period, ring annuloplasty was associated with lesser residual regurgitation and better right ventricular remodeling in severe functional tricuspid regurgitation than DeVega procedure after 6-months of follow up.

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